Lens barrel and camera system

ABSTRACT

A lens barrel includes an oscillatory wave motor which drives a lens; a manual connection ring which is operated manually to cause the lens to move along an optical axis; a slip ring which is in contact with the manual connection ring; a roller which is in contact with the slip ring and with the oscillatory wave motor; and a roller support ring which supports the roller. The slip ring is structured such that frictional resistance on a contact surface between the manual connection ring and the slip ring is smaller than frictional resistance on a contact surface between the roller and the slip ring.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.12/969296, filed Dec. 15, 2010, which claims priority from JapanesePatent Application No. 2009-289724 filed Dec. 21, 2009, which is herebyincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel in which lenses can bedriven by an annular oscillatory wave motor disposed coaxially with anoptical axis and in which lenses can be operated manually with a manualring.

2. Description of the Related Art

Japanese Patent Laid-Open No. 02-253214 discloses a lens barrel in whichlenses can be driven by an oscillatory wave motor with a ring havingrollers rotatable about axes disposed at radial positions thereof(hereinafter, referred to as a roller support ring) and in which lensescan be operated manually with a manual operation ring.

With the structure disclosed in Japanese Patent Laid-Open No. 02-253214,when a user tries to continue to manually operate the manual operationring after the roller support ring is brought into contact with anoperating end, a portion with the smallest frictional resistance slipsagainst frictional force. Usually, the portion slips at a place betweenthe manual operation ring and the rollers, between the rollers and theoscillatory wave motor or, though in rare cases, between a rotor and astator in the oscillatory wave motor. The roller support ring often hasa complicated shape and is thus formed by resin molding. When a slippageof the rollers which are supported by shafts that are made of resin andare thus easily elastically deformable occurs, deformation of the shaftand friction may be caused alternately and repeatedly. This phenomenonmay cause undesirable vibration and unusual noise.

The present invention reduces slippages between a roller and a member incontact with the roller when an operator tries to continue a manualoperation after a roller support ring is brought into contact with anoperating end.

SUMMARY OF THE INVENTION

An exemplary lens barrel according to the present invention includes: anannular oscillatory wave motor which drives a lens; a manual ring whichis rotatable about the optical axis of the lens and is operated manuallyto move the lens along the optical axis; a slip ring which is rotatableabout the optical axis and is in contact with the manual ring; a rollerwhich is rotatable about an axis in a radial direction perpendicular tothe optical axis and is in contact with the slip ring and with theoscillatory wave motor; a roller support ring which supports the rollerand is rotatable about the optical axis; and a pressurizer which pressesthe oscillatory wave motor against the roller. The slip ring isstructured such that frictional resistance on a contact surface betweenthe manual ring and the slip ring is smaller than frictional resistanceon a contact surface between the roller and the slip ring.

Another exemplary lens barrel according to the present inventionincludes: an annular oscillatory wave motor which drives a lens along anoptical axis; a manual ring which is rotatable about the optical axis ofthe lens and is operated manually to move the lens along the opticalaxis; a slip ring which is rotatable about the optical axis and is incontact with the manual ring; a roller which is rotatable about an axisin a radial direction perpendicular to the optical axis and is incontact with the slip ring and with the oscillatory wave motor; a rollersupport ring which supports the roller and is rotatable about theoptical axis; and a pressurizer which presses the roller and the slipring together by pressing the oscillatory wave motor against the roller.A contact surface between the manual ring and the slip ring and acontact surface between the roller and the slip ring are adapted suchthat a slippage might occur between the manual ring and the slip ringbefore a slippage occurring between the roller and the slip ring whenthe manual ring receives force in a predetermined rotational directioneven after it is rotated in the predetermined rotational direction andis brought into contact with an end of a rotational area.

Further features of the present invention will become apparent from thefollowing description of an exemplary embodiment with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a lens barrel to which the presentinvention is applied.

FIG. 2 is a partially enlarged sectional view of a focus driving unit.

FIG. 3 is an exploded perspective view of the focus driving unit.

FIG. 4 illustrates a camera system.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a lens barrel according to an embodiment of the presentinvention will be described with reference to the drawings.

The lens barrel according to the present embodiment incorporates anannular oscillatory wave motor disposed coaxially with an optical axisof lenses and includes a manual operation ring which enables a manualoperation.

FIG. 1 is a sectional view of the lens barrel according to the presentembodiment. FIG. 2 is a partially enlarged view of FIG. 1 (i.e., in abroken line frame A) illustrating a focus driving unit included in thelens barrel. FIG. 3 is an exploded perspective view of the focus drivingunit. FIG. 4 illustrates a camera system constituted by the lens barreland a camera body.

A lens barrel 300 according to the present embodiment includes a mount201 for mounting on a camera body 310. The mount 201 includes aconnector 202 for the communication between the camera body 310 and thelens barrel 300.

The mount 201 is attached with screws to a fixed lens barrel 203. Thefixed lens barrel 203 is fixed with screws to an intermediate barrel204. The intermediate barrel 204 is attached with screws to a guidebarrel 205. An exterior barrel 206 is attached with screws to theintermediate barrel 204. The fixed lens barrel 203, the intermediatebarrel 204 and the guide barrel 205 are annular members disposedcoaxially with the optical axis.

A first lens barrel 207 which supports a first lens unit L1 is fit intoand supported by the guide barrel 205 at the side closest to an object.A cam follower A 210 which is fit into a cam slot of the guide barrel205 is fixed with screws to the first lens barrel 207. An opticaladjustment during manufacture of the lens barrel 300 can be made via thecam follower A 210 by moving the first lens barrel 207 back and forthwithin the cam slot of the guide barrel 205.

A cam barrel 208 is fit into the guide barrel 205. A cam follower B (notillustrated) is fixed with screws to the cam barrel 208. The camfollower B is fit into a slot formed inside the guide barrel 205 androtates at a fixed position about the optical axis along an innerdiameter of the guide barrel 205. A sub cam barrel 209 is fit into thecam barrel 208. A cam follower C (not illustrated) is fixed with screwsto the sub cam barrel 209. The cam follower C is made to pass through anin-line slot formed in the cam barrel 208 and in a sub cam slot formedin the guide barrel 205. The sub cam barrel 209 is moved back and forthalong the inner diameter of the cam barrel 208 as the cam barrel 208rotates.

A second in-line guide barrel 211 is fit into the sub cam barrel 209.The second in-line guide barrel 211 is fixed to the sub cam barrel 209through a bayonet engagement and is capable of rotating at a fixedposition about the optical axis within the sub cam barrel 209. Thesecond in-line guide barrel 211 includes an in-line slot and a slot inwhich a focus key 107 of a focus driving unit 2A is fit.

A second lens barrel 212 which supports a second lens unit L2 is fitinto the second in-line guide barrel 211. A cam follower D 213 is fixedwith screws to the second lens barrel 212. The cam follower D 213 ismade to pass through a focus cam slot formed in the sub cam barrel 209and through an in-line slot of the second in-line guide barrel 211. Athird in-line guide barrel 214 is fit into the sub cam barrel 209. Thethird in-line guide barrel 214 is fixed to the sub cam barrel 209through a bayonet engagement and is capable of rotating at a fixedposition about the optical axis within the sub cam barrel 209. The thirdin-line guide barrel 214 includes an in-line slot and a slot into whichan in-line guide key 216 fixed to the guide barrel 205 is fit.

A third lens barrel 215 which supports a third lens unit L3 is fit intothe third in-line guide barrel 214. A cam follower E (not illustrated)is fixed with screws to the third lens barrel 215. The cam follower E ismade to pass through a zoom cam slot formed in the sub cam barrel 209and through an in-line slot of the third in-line guide barrel 214.

A cam follower F 218 is fixed with screws to a fourth lens barrel 217which supports a fourth lens unit L4. The cam follower F 218 is made topass through a fourth cam slot formed in the cam barrel 208 and throughan in-line slot formed in the guide barrel 205.

A zoom operation ring 219, a gear ring A 220 engaging with screws withthe zoom operation ring 219 and a gear ring B 221 are fit into andsupported by the intermediate barrel 204. The gear ring A 220 and thegear ring B 221 rotate at fixed positions about the optical axis alongan outer diameter of the intermediate barrel 204. A gear unit 222 whichrolls between the gear ring A 220 and the gear ring B 221 is fixed withscrews to the intermediate barrel 204. A zoom lever 223 is fixed withscrews to the gear ring B 221 at one end and fit into the cam barrel 208at the other end.

A focus ring 224 is fit onto the guide barrel 205. A cam follower G (notillustrated) which is fixed with screws to the guide barrel 205 is fitinto a slot 224 a formed inside the focus ring 224. The focus ring 224is rotated at a fixed position about the optical axis along an outerdiameter of the guide barrel 205. The focus ring 224 engages with amanual connection ring 102 provided inside the focus driving unit 2A.The manual connection ring 102 transfers torque from the focus ring 224to the focus driving unit 2A. An end surface of the manual connectionring 102 along the optical axis is in contact with the guide barrel 205and is positioned along the optical axis by the guide barrel 205.Although the manual connection ring 102 and the focus ring 224 areseparately provided in the present embodiment, these components may beformed integrally with each other. From this reason, the manualconnection ring 102 and the focus ring 224 are collectively referred toas “a manual ring.”

The focus driving unit 2A is formed by a differential operating systemwhich will be described later and torque output from the differentialoperating system is transferred to the second in-line guide barrel 211via the focus key 107. The focus key 107 and the in-line slot of thesecond in-line guide barrel 211 are fit together.

An electrically operated aperture unit 2C is provided at an imagingsurface side of the fourth lens barrel 217. At an imaging surface sideof the electrically operated aperture unit 2C, a fifth lens barrel 225which supports a fifth lens unit L5 is fit into the intermediate barrel204 and is supported at a fixed position by a cam follower H (notillustrated).

A sixth lens unit L6 is an image stabilization lens unit. The positionof the imaging surface is changed as the sixth lens unit L6 is movedalong a face perpendicular to the optical axis. An image stabilizationlens unit 2B includes a sixth lens barrel 226 which supports the sixthlens unit L6, two pairs of magnets for driving the sixth lens unit L6 intwo axial directions, a coil, a lens position detecting element and adrive controlling substrate which controls these components. The imagestabilization lens unit 2B is fit into the intermediate barrel 204 andis supported at a fixed position by a cam follower I (not illustrated).

A seventh lens barrel 227 which supports a seventh lens unit L7 is fixedwith screws to the intermediate barrel 204 at an end surface of theimaging surface side. A gyro sensor which detects angular velocity alongthe two axes and two substrates which control the lens barrel areattached to the seventh lens barrel 227.

The lens barrel includes a plurality of devices which output states ofthe lenses. The devices output, to the camera body, focal distanceinformation, focusing unit position information, focus displacementinformation, information on aperture opening, information on an imagestabilization lens position, lens angular velocity information, andother information.

Next, a structure of the focus driving unit 2A will be described indetail.

As illustrated in FIGS. 1 to 3, the guide barrel 205 also functions as abase member of the focus driving unit. The guide barrel 205 supports acollar member 101 which is provided to reduce frictional resistance. Themanual connection ring 102 is attached in contact with the collar member101. A slip ring 103 is disposed in contact with the manual connectionring 102. Rollers 105 are disposed in contact with the slip ring 103 atthree radial positions perpendicular to the optical axis of the lensbarrel. The manual connection ring 102 and the slip ring 103 arerotatable about the optical axis as will be described in detail later.

Contact surfaces between the manual connection ring 102 and the slipring 103 and between the slip ring 103 and the rollers 105 each havesurface roughness determined such that frictional resistance between themanual connection ring 102 and the slip ring 103 might be smaller thanthat between the slip ring 103 and the rollers 105.

The rollers 105 are supported to rotate about support shafts disposed atthree radial positions on a circumference of a roller support ring 104.Each of the rollers 105 is retained on its shaft with a washer 106. Thefocus key 107 is fixed to the roller support ring 104 in engagement withthe second in-line guide barrel 211. A brush member 108 is attached tothe roller support ring 104 at a position corresponding to a flexibleprinted wiring board (not illustrated) attached to the guide barrel 205and provided with a printed gray code pattern. The flexible printedwiring board and the brush member 108 constitute a position encoder. Asthe brush member 108 slides on the flexible printed wiring board, arotational position of the roller support ring 104 is detected. Thedetected rotational position of the roller support ring 104 is used forthe control of a focusing operation. A distance scale sheet 118 having aprinted scale corresponding to a rotation angle is attached to an outercircumference of the roller support ring 104. A rotational area of theroller support ring 104 with respect to the guide barrel 205 isrestricted by an unillustrated rotation control portion such that theroller support ring 104 is moved within an operation area of the secondlens unit L2 which is a focusing unit.

A connection ring 109 is disposed in contact with the slip ring 103 andwith the rollers 105, which are in contact with the slip ring 103, atthe imaging surface side thereof. An annular oscillatory wave motor isdisposed coaxially with the optical axis of the lenses at the imagingsurface side of the connection ring 109 via a rubber sheet 110. Theoscillatory wave motor is constituted by a rotor 111, a stator 113 and apiezoelectric element 114. A dustproof collar 112 is provided to fix arotational mounting position of the stator 113 and to reduce ingressionof wear debris generated on a contact surface between the rotor 111 andthe stator 113 toward the flexible printed wiring board. A pressurizeris constituted by a felt sheet 115, a spring washer 116 and a thrustwasher 117. The pressurizer applies urging force along the optical axisto the components constituting the oscillatory wave motor such that thecomponents are brought into contact with one another. With the urgingforce, the rotor 111 of the oscillatory wave motor is pressed againstthe rollers 105 via the rubber sheet 110 and the connection ring 109which is formed integrally with the rotor 111.

Next, an operation of the focus driving unit 2A will be described.

In a motor-driven focus control in, for example, an auto focusingsystem, the oscillatory wave motor is driven in accordance with acontrol instruction from the camera body. The rollers 105 which theconnection ring 109 disposed integrally with rotor 111 is in contactwith are rotated by torque of the rotor 111 which is an output part ofthe oscillatory wave motor. At the same time, the roller support ring104 which supports the rollers 105 is rotated about the optical axis ina forward direction at a reduction ratio of 1/2. The focus key 107,which is fixed to the roller support ring 104, engages with the secondin-line guide barrel 211 such that the second lens unit L2 which is afocusing unit might be moved by the focus key 107. The position encoderconstituted by the flexible printed wiring board and the brush member108 detects an end of the operation area. It is therefore controlledthat no excessive torque might be applied to the oscillatory wave motor.

Next, an operation following a manual operation of the focus ring 224will be described.

As the focus ring 224 is rotated, torque is transferred to the manualconnection ring 102 engaging therewith. At the same time, torque istransferred to the slip ring 103 which is disposed integrally with themanual connection ring 102. The slip ring 103 is pressed against therollers 105. The oscillatory wave motor is disposed at the imagingsurface side of the rollers 105. Accordingly, as the slip ring 103 isrotated about the optical axis, the rollers 105 are rotated and thus theroller support ring 104 supporting the rollers 105 are rotated in aforward direction. As the roller support ring 104 is rotated about theoptical axis, the focus key 107 engages with and moves the second lensunit L2, which is the focusing unit, in the same manner as being drivenby the oscillatory wave motor.

Next, an operation in which an operator tries to rotate the focus ring224 after the roller support ring 104 is brought into contact with anend of a rotational area will be described. A slippage occurs betweenthe manual connection ring 102 and the slip ring 103 before a slippageoccurring between the slip ring 103 and the rollers 105. This is becausefrictional resistance between the manual connection ring 102 and theslip ring 103 is smaller than that between the slip ring 103 and therollers 105. The slippage between the rollers 105 and the slip ring 103which are in surface contact with each other can reduce an occurrence ofundesired unusual noise.

Next, an operation in which the operator performs a zooming operationwith the lens barrel (i.e., operates the zoom operation ring 219) willbe described.

An operation of the zoom operation ring 219 causes the gear ring A 220to rotate and thereby causes the gear unit 222 to rotate. Thus, the gearring B 221 is rotated in a reverse direction. Torque of the gear ring B221 is transferred to the cam barrel 208 via the zoom lever 223 asreverse torque with the rotation of the zoom operation ring 219. Sincethe cam follower B is fit into the slot formed inside the guide barrel205, the cam barrel 208 rotates at a fixed position about the opticalaxis along the inner diameter of the guide barrel 205.

Since the cam follower C attached to the sub cam barrel 209 fitting intothe cam barrel 208 is fit into the in-line slot of the cam barrel 208,the sub cam barrel 209 rotates in an amount equivalent to that ofrotation of the cam barrel 208 as the cam barrel 208 rotates. Since thecam follower C attached to the sub cam barrel 209 is fit also into thecam slot of the guide barrel 205, the sub cam barrel 209 is moved backand forth along the cam slot of the guide barrel 205. Thus, the sub cambarrel 209 is extended while being rotated within the cam barrel 208.

Since the second in-line guide barrel 211 which is fit into the sub cambarrel 209 is fixed to the sub cam barrel 209 through a bayonetengagement, the second in-line guide barrel 211 tries to rotate in anamount equivalent to that of rotation of the sub cam barrel 209 due tothe frictional force of the portion at which the second in-line guidebarrel 211 and the sub cam barrel 209 are fit together. The focus key107 of the focus driving unit 2A engages with the second in-line guidebarrel 211. The focus key 107 of the focus driving unit 2A is fixed tothe differential operating system within the focus driving unit 2A. Thedifferential operating system is supported by friction. The focus key107 may receive force from the second in-line guide barrel 211 in therotational direction. Even in that case, since frictional support forceof the differential operating system is larger than frictional supportforce between the sub cam barrel 209 and the second in-line guide barrel211, the focus key 107 would not be rotated.

The cam follower D 213 of the second lens barrel 212 is made to passthrough and supported by the focus cam slot formed in the sub cam barrel209 and the in-line slot of the second in-line guide barrel 211. Thus,the second lens barrel 212 is moved linearly within the second in-lineguide barrel 211.

Since the third in-line guide barrel 214 which is fit into the sub cambarrel 209 is fixed to the sub cam barrel 209 through a bayonetengagement, the third in-line guide barrel 214 tries to rotate in anamount equivalent to that of rotation of the sub cam barrel 209 due tothe frictional force of the portion at which the third in-line guidebarrel 214 and the sub cam barrel 209 are fit together. When the sub cambarrel 209 is extended while being rotated within the cam barrel 208,the third in-line guide barrel 214 tries to rotate interlockingly withthe sub cam barrel 209 such that the sub cam barrel 209 might to beextended. The third in-line guide barrel 214 is moved linearly with thesub cam barrel 209 while rotation of the third in-line guide barrel 214is restricted by the in-line guide key 216 which is fixed to the guidebarrel 205.

The cam follower E of the third lens barrel 215 is made to pass throughand supported by a third cam slot formed in the sub cam barrel 209 andthrough an in-line slot of the third in-line guide barrel 214. As thecam barrel 208 is rotated and the sub cam barrel 209 is rotated andextended, the cam follower E of the third lens barrel 215 is moved backand forth along the cam slot of the sub cam barrel 209. Thus, the thirdlens barrel 215 is moved, without rotation, along the optical axis in anamount greater than that of the movement of the sub cam barrel 209 alongthe optical axis.

In the fourth lens barrel 217, the cam follower F 218 which is fixedthereto with screws is made to pass through a fourth cam slot formed inthe cam barrel 208 and through an in-line slot formed in the guidebarrel 208. Thus, as the cam barrel 208 rotates, the cam follower F 218of the fourth lens barrel 217 is moved along the fourth cam slot of thecam barrel 208. Since the cam follower F 218 is fit also into thein-line slot of the guide barrel 208, the cam follower F 218 is movedonly along the optical axis without rotation. Thus, as the cam barrel208 is rotated, the fourth lens barrel 217 is moved linearly back andforth within the cam barrel 208.

Accordingly, a focal length of the lens barrel is changed with therotation of the zoom operation ring 219.

While a preferred embodiment of the present invention has beendescribed, it is to be understood that the present invention is notlimited thereto but may be changed or modified within the spirit andscope of the present invention.

For example, as described above, the manual connection ring 102 and thefocus ring 224 are provided as separate parts for the ease ofmanufacture. However, these parts may be integrated without limiting theeffect of the present invention. The collar member 101 may be formed asa sheet member with slidability. While the rollers 105 are disposed atthree radial positions perpendicular to the optical axis and at equalintervals, four or more rollers 105 may be provided. Each of the rollers105 may alternatively have two stepped diameters such that the slip ring103 and the connection ring 109 are brought into contact with therollers 105 at different diameter sections. With this, there is also aneffect that the reduction ratio of the roller support ring 104 can bechanged independently for the manual operation and for the motor-drivenoperation.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A lens barrel, comprising: an annular oscillatorywave motor which drives a lens along an optical axis; a manual ringwhich is rotatable about the optical axis of the lens and is operatedmanually to move the lens along the optical axis; a slip ring which isrotatable about the optical axis and is in contact with the manual ring;a roller which is rotatable about an axis in a radial directionperpendicular to the optical axis and is in contact with the slip ringand is driven by the annular oscillatory wave motor; a roller supportring which supports the roller and is rotatable about the optical axis;and a pressurizer which presses the roller and the slip ring, whereinfrictional resistance on a contact surface between the manual ring andthe slip ring is smaller than that on a contact surface between theroller and the slip ring.
 2. The lens barrel according to claim 1,wherein radius of the slip ring is smaller than that of the manual ring.3. The lens barrel according to claim 1, wherein: the roller supportring includes a driving arm which engages, upon rotation, with a guidebarrel that causes the lens to move along the optical axis; and as thedriving arm provided in the roller support ring is rotated about theoptical axis by the annular oscillatory wave motor or the manual ring,the guide barrel is rotated to cause the lens to move along the opticalaxis.
 4. The lens barrel according to claim 1, wherein the manual ringincludes an operation ring to be rotated by a manual operation and amanual connection ring configured to transfer rotation of the operationring to the slip ring.
 5. A camera system comprising the lens barrelaccording to claim
 1. 6. A lens barrel, comprising: an annularoscillatory wave motor which drives a lens along an optical axis; amanual ring which is rotatable about the optical axis of the lens and isoperated manually to move the lens along the optical axis; a slip ringwhich is rotatable about the optical axis and is in contact with themanual ring; a roller which is rotatable about an axis in a radialdirection perpendicular to the optical axis and is in contact with theslip ring and is driven by the annular oscillatory wave motor; a rollersupport ring which supports the roller and is rotatable about theoptical axis; and a pressurizer which presses the roller and the slipring, wherein a contact surface between the manual ring and the slipring and a contact surface between the roller and the slip ring areadapted such that a slippage might occur between the manual ring and theslip ring before a slippage occurring between the roller and the slipring when the manual ring receives force in a predetermined rotationaldirection even after it is rotated in the predetermined rotationaldirection and is brought into contact with an end of a rotational area.7. The lens barrel according to claim 6, wherein radius of the slip ringis smaller than that of the manual ring.
 8. The lens barrel according toclaim 6, wherein: the roller support ring includes a driving arm whichengages, upon rotation, with a guide barrel that causes the lens to movealong the optical axis; and as the driving arm provided in the rollersupport ring is rotated about the optical axis by the annularoscillatory wave motor or the manual ring, the guide barrel is rotatedto cause the lens to move along the optical axis.
 9. A camera systemcomprising the lens barrel according to claim
 6. 10. The lens barrelaccording to claim 6, wherein the manual ring includes an operation ringto be rotated by a manual operation and a manual connection ringconfigured to transfer rotation of the operation ring to the slip ring.